OnClick # -> JS alert with content

How to?
#1

Hi

I have a link # which produces a JS alert. How could I scrape out the telephone number?

See code below.

Thanks

<div class="grid_2" style="width:35px;">
         <a href="#" onclick="alert('+3179512345');">
      <img src="https://domain/images/icon.png" width="35">
                            </a>
                            <br/>
    </div>